Wow. NPR national political correspondent Mara Liasson is here to tell us what yesterday's races mean.

Mara, good morning.

MARA LIASSON, BYLINE: Good morning.

INSKEEP: OK, let's use Kentucky as an example here. How would that race had been different if Mitch McConnell was gone and the Tea Party candidate was nominated?

LIASSON: Well, the Democrats would be very happy and much more optimistic. The Democrats really were the losers yesterday in Kentucky and across the board. They wanted the most conservative, most undisciplined Republican candidates, most under-funded, to win. And they lost almost everywhere.

The other thing that happened in Kentucky is immediately after the polls closed, the Tea Party closed ranks behind Mitch McConnell. So he's got a united Republican Party going into the fall against Alison Lundergan Grimes.

INSKEEP: And that possibility of $100 million being spent in a single state and then...

LIASSON: In Kentucky.

INSKEEP: Yeah.

LIASSON: Not a very expensive state.

INSKEEP: Not the largest state by any means.

LIASSON: Right, right.

INSKEEP: Now, then there's Georgia. Several Republicans were trying to take on the Democrat, Michelle Nunn. There's a runoff now, but as I understand it, neither of the two Republicans who got into the runoff is considered the most conservative candidate who was in the race.

LIASSON: Well, that's right. Georgia was the other state, other than Kentucky, where Democrats had hopes of picking up a seat. Now the two establishment backed candidates, David Perdue and Jack Kingston, handily beat their Tea Party challengers. They go into a runoff. It will take nine weeks. It will be bloody and expensive and the winner faces Michelle Nunn, the Democrat, in the fall.

INSKEEP: Is that dangerous for the Republicans, simply that they're in a runoff in a vital seat?

LIASSON: Well, a runoff was expected. It was almost unavoidable. Of course they'd rather have a candidate right now running against Michelle Nunn, but they have to get through the runoff. Georgia is still going to be a very, very tough state for Democrats to win, even though the population there is changing and Democrats have hopes of turning it blue in the future.

INSKEEP: We're getting a little repetitive here, Mara. Oregon, also the more conservative Republican in the primary was defeated.

LIASSON: Yes. This is the theme this year. Republicans hope to expand the map, the battleground map beyond red states. They think they found a perfect candidate to run in light blue Oregon. She's Monica Wehby, a woman, pediatric neurosurgeon, mother of four. She's very well-funded and she easily dispatched her Tea Party challenger, her opponent, Jason Conger, last night.

INSKEEP: So how are Republicans feeling about November at this point and what can you tell from yesterday's primary races about the way that this fight for Congress, with the Senate especially on the line, is going to shape up?

LIASSON: Well, I think Republicans are feeling they've expanded the map about as much as they can. There's also something else important that's been happening in these primaries. You know, we've been talking about how the Tea Party has been winning the war, if not the individual primary races. Just yesterday, House Speaker John Boehner said there was not much difference between regular conservatives and the Tea Party.

But something important is happening here that could affect how Congress operates at the margins, and that is that the establishment believes it's sending a very important message to Republican members. They're saying if you are worried about getting a primary challenge from the Tea Party, don't be afraid. Don't be afraid to follow the Republican leadership on controversial issues. Don't be afraid to even cross the aisle on some occasions.

We have your back. We will support you in a primary. We will come in and spend a lot of money, and in these primaries that we've seen over the past couple of weeks, they've proved that they can and will do that.

INSKEEP: Well, how big a factor has that fear of Republican primary fights been in Congress in the last several years? How huge has that been in our politics?

LIASSON: Well, it's been very, very big because for many reasons, gerrymandering is one reason, the population sorting itself out is another, most members are in very safe districts. Most House incumbents win with more than 55 percent of the vote. Their biggest worry is a primary. And now they've got some insurance from these establishment groups who finally decided to play, to vet candidates, to spend money, and I think that that fear level will go down a bit.

INSKEEP: Still some primaries to come.

LIASSON: Very important primaries to come in Mississippi, early June we've got Thad Cochran, the incumbent, running against a Tea Party challenger, Chris McDaniels. But there's something else I'm looking forward to, August in Michigan, Justin Amash, House member, leader of the Tea Party caucus. He's a libertarian. A lot of business groups are coming in to try to defeat him. This is different than fending off a Tea Party challenge to an incumbent.

This is the establishment going after a sitting member. If he loses in the primary, that will be a very big deal.

INSKEEP: Okay. And we'll be watching and listening for your commentary on that. Mara, thanks as always.

LIASSON: Thank you.

INSKEEP: That's NPR national political correspondent Mara Liasson on this morning after primaries in six states. Mitch McConnell of Kentucky among the winners. It's MORNING EDITION from NPR News. Transcript provided by NPR, Copyright NPR.